The present patent document is a continuation-in-part of PCT international application No. PCT/CN2009/072151 filed on Jun. 5, 2009, the entire content of which are hereby incorporated herein by reference.
The present invention relates to an LED light module and method of manufacturing the same, and especially to an LED light module for street lamp with elongated light beam and a method of manufacturing the same.
A known LED light module as described in Chinese Pat. No. ZL200710030627.1 to Fan includes a base for fixing electrodes and a heat sink. The heat sink supports an LED chip thereon. A transparent cover is substantially in a shape of hemisphere, and is secured over the base so as to shield the LED chip therein. However, when Fan's LED light module is used for street lamp, the exit light beam has a round periphery. This means that the peripheral light beam will intercept a smaller road surface. The maximum distance between two consecutive street luminaries is limited, and the light uniformity and intensity is poor. Usually, an additional reflector or light-beam shaper is necessary to be provided to the luminary head, across the light path, in order to direct the light beam with an appropriate angle, towards the street. It is complex, inconvenient, and costly for using the additional reflector. Fan also discloses a method of manufacturing the transparent cover. However, the method is completely a manual operation, thus it is in very poor efficiency.
A known light-beam shaper in the art as one described in international publication No.: WO2008/122941 to Louis. The Louis's light-beam shaper comprises an entry diopter, an exit diopter, and a base surface. The exit diopter includes a first convergent section, a second convergent section and a divergent section bridging the first and second convergent sections. The light-beam shaper is mounted over the LED for redistributing the light flux, and the redistribution results in an elongate light beam with symmetrical light distribution lengthwise. However, the LED device has some disadvantages. Firstly, Louis's light-beam shaper is an extra component for an LED device, which is costly and complex structure. Secondly, Louis's light-beam shaper is not an integral structure for the LED device, and an undesirable space exists between the LED and the shaper. As a result, dust, water, ice, snow or the like will easily enter from the space and the base surface to destroy the LED. Especially when it is necessary to solder the LED device onto the PCBA, solder and heat will enter from the space to destroy the LED. Thirdly, the entry diopter is a convex, which defines an inner space for lodging the LED. Light beam exited from LED passes through the space, then from the entry diopter to the exit diopter, which will result in light loss in the space and the entry diopter. Furthermore, some light beam will leak out from the base surface, which results in light loss and light pollution. Finally, the light-beam shaper is made from polymethacrylate, the melting point of which is relatively low, it is not applicable for the soldering process of LED device to the PCBA since heat or solder will destroy the light beam shaper.
Therefore, an improved LED light module for street lamp is desired which overcomes the disadvantages of the prior art.